Nick’s message, use T-Mobile cellular access Live Cameras remotely via iPhone. It has the issue only working in WiFi, but not in cellular mode (data plan) remote. He found the answer:

“Good news…..it’s now working! After trying everything I went into my phone settings to verify my iPhone version and while I was in it a “carrier update available” popped up. I updated it and now I can see my cameras again. It was definitely a T-mobile issue. My understanding was that they switched to Ipv6 and it was having problems converting Ipv4 things. I guess they fixed it. Thanks for all your help!”